For reference to prior art couplings, attention is directed to the prior art Hengst U.S. Pat. No. 2,451,218, issued Oct. 12, 1948; the Main, Jr. U.S. Pat. No. 2,451,441, issued Oct. 12, 1948; the Main, Jr. U.S. Pat. No. 2,457,251, issued Dec. 28, 1948 and the Hansen U.S. Pat. No. 2,548,528, issued Apr. 10, 1951.
Attention is further directed to the Pearson U.S. Pat. No. 3,500,859, issued Mar. 17, 1970; the Hodson U.S. Pat. No. 3,196,897, issued July 27, 1965; and the Collar U.S. Pat. No. 3,191,972, issued June 29, 1965.
Attention is further directed to the Johnson U.S. Pat. No. 3,550,624, issued Dec. 29, 1970 and the De Visscher U.S. Pat. No. 3,777,771, issued Dec. 11, 1973.